1. Field of the Invention
The present invention relates generally to the field of stringed musical instruments, especially to those of the plucked rather than the bowed types, and more particularly to apparatus for supporting the strings of the instrument and for enabling harmonic and pitch adjustment of the strings.
2. Discussion of the Prior Art
It is, of course, well known that such stringed musical instruments as guitars have a number of side-by-side strings which are stretched along a relatively slender, elongated neck of the instrument. One end of each string is individually attached to a bridge mounted to the body of the instrument and the other end of each string is connected to individual string tensioning apparatus, for example, a manually turnable tuning peg, mounted to, or formed as a part of the instrument head.
Most such instruments are also constructed so as to have string break points relatively adjacent to both end attachments over which the strings pass and which establish the vibrational length of the strings. Such string break points are typically provided by a so-called nut at the head of the instrument and by string saddles mounted to the bridge. Typically apparatus is provided at the bridge for moving the saddles on an individual basis to adjust the vibrational or harmonic length of the individual strings. Gross and fine string tensioning or pitch adjustments are provided as well. Ordinarily, the tuning pegs provide the gross tensioning; whereas, fine pitch adjustment is typically provided by adjusting screws associated with the bridge.
On many such plucked string instruments as guitars, the bridge is mounted for enabling manual pivoting, to thereby simultaneously change the pitch (tension) of all the strings to produce a vibrato effect. Such bridges, typically called tremulo bridges, are pivotally mounted to the instrument body and are maintained in a normal, string tensioned position by strong springs against which the tensioned strings pull. A protruding tremulo lever mounted to the bridge enables the instrument player to pivot the bridge so as to slacken the strings and change string pitch. Upon release of the tremulo lever, the springs return the bridge to the normal, static position for which the instrument is tuned.
As may be appreciated, the repeated and often violent slackening and retensioning of the strings by operation of the tremulo bridge during playing of the instrument makes keeping the instrument in tune very difficult. For example, when the strings are slackened, the coils of the strings around the tuning pegs loosen. These loosened coils are not, however, instantaneously tightened when the tremulo lever is released and so the tensioning (pitch) of the strings changes while the coil retightening continues. To eliminate such pitch change problems, string clamps may be provided between the nut and the tensioning pegs, usually closely adjacent to the nut. After the unclamped strings have been properly tensioned by turning of the tuning pegs, the strings are tightly clamped at the nut-end string break point. As a result, slackening of the strings by operation of the tremulo bridge does not affect the portion of the strings between the nut-end string clamps and the tuning pegs. In a like manner, string clamps are usually provided between the string saddle and the string attachment at the bridge.
Particular problems are, however, associated with nut-end string clamping. The instruments may ordinarily require some tuning or retuning during play, as a result, for example, of the strings being stretched by rough playing and repeated operation of the tremulo bridge. Typically, the necessary string retensioning is most conveniently accomplished by relatively slight manual adjustments of the tuning pegs. It can, however, be appreciated that the tuning pegs cannot be used to retension the strings unless the strings are first unclamped at the nut. Thus, to retension the strings by use of the tuning pegs, the strings must be unclamped, the tuning peg adjustment made and the strings then reclamped. Because of the close, side-by-side spacing of the strings at the nut clamps, such clamps ordinarily require the use of a tool to operate, thereby making clamping and unclamping of the strings both inconvenient and time consuming, and therefore usually impractical for "on-stage" tuning of the instruments.
At the bridge, provisions are generally made to enable fine pitch tuning of the strings without changing the location of the bridge-end string break point. That is, so that the fine pitch tuning operation does not change the vibrational length of the strings. For example, U.S. Pat. No. 4,497,236 to Rose, discloses roller-type saddles over which the strings are passed and which form or define the bridge-end string break point. After passing over radially curved portions of the rollers, the strings are clamped to flattened regions of the rollers. Fine pitch tuning is provided by apparatus which operate on extending arm portions of the clamps so as to cause partial rotation of the rollers against which the strings are clamped. The initial contact of the strings as they pass from the instrument neck over the rollers defines the bridge end break point, and as the rollers are partially rotated, to adjust string pitch, the string break point stays fixed relative to the bridge. As a result, the harmonic or vibrational length does not change as a string is pitch tuned.
However, due both to manufacturing tolerances and side clearances required to assure free pivoting of such rollers, some amount of lateral roller play is inevitable. Consequently, a corresponding amount of lateral string movement is permitted where the strings are supported by these rollers. It has been found and is generally known that when the instrument is played, such lateral string movement at the break point, even though the lateral movement may be only a very few thousandths of an inch, causes the instrument to have poor sound sustaining qualities. That is to say, only slight lateral string movement at the bridge-end break point results in a noticeable reduction in the length of time the strings keeps vibrating after they are plucked.
It has further been determined that the small amount of lateral string movement permitted by roller supporting of the strings at the bridge has very much more of an adverse musical effect than would any change in vibrational length of the strings caused by pitch adjustment if rollers were not used to maintain a constant string vibrational length.
For these and other reasons, improvements to string supporting and clamping apparatus for use on such stringed instruments as guitars are needed in order to improve the convenience of tuning while at the same time improving sound sustaining qualities of the instrument.